1. Field of the Invention
The invention relates to a magnetic resonance apparatus, including a magnet system for generating a steady magnetic field in a measurement space, a gradient coil system for generating gradient fields in the measurement space, and a number of gradient amplifiers with input terminals which are connected to means for generating an input signal exhibiting a predetermined variation as a function of time, and output terminals, the output terminals of at least one of the gradient amplifiers being connected to an output circuit which comprises a series connection of a gradient coil and at least one capacitor.
2. Description of the Related Art
An apparatus of this kind is known from EP-A-0 389 666 which corresponds to U.S. Patent No. 5, 079,503. The gradient coil in the known apparatus constitutes a series resonant circuit in conjunction with one or two capacitors. The cited document explains that as a result the voltage across the gradient coil may be substantially higher than the output voltage of the gradient amplifier. This is because a boost effect occurs when the resonant circuit operates in resonance, so that the voltage across the gradient coil may become very high. In this situation the gradient amplifier need merely compensate for the voltage loss across the ohmic resistance of the gradient coil. The current through the gradient coil equals the output current of the gradient amplifier.